River Tam was the teenage sister of Dr. Simon Tam, both of whom take refuge aboard Malcolm Reynolds' Firefly-class transport ship known as Serenity. She is considered a child prodigy, intelligent beyond her years and athletically gifted. After intense experimentation by Dr. Mathias on behalf of the Parliament—the Alliance ruling body—River was partially transformed into a mentally unstable psychic weapon intended for secret governmental use. She was rescued at great cost by her brother Simon but tracked relentlessly by several agents of the Alliance, primarily Lawrence Dobson, two blue-gloved men, McGinnis, the bounty hunter Jubal Early, and finally the Operative. Almost all of her time on the lam was spent with the crew of the Serenity, who became her extended family.